Here’s an example. Let’s say that you turn on a lamp with a 100 watt bulb at 6:00 p.m. and turn it off at 11:00 p.m. It takes 100 watts to light the bulb.

100 watts = 100 ÷ 1000 kilowatt = 1 ÷ 10 kilowatts = 0.1 kilowatts

So, the light bulb will use 0.1 kilowatts. But, the light will be on for 5 hours (from 6:00 p.m. until 11:00 p.m.). So, the lamp will use 0.1 kilowatts for 5 hours

0.1 kilowatts x 5 hours = 0 .5 kilowatt hours

Electricity rates vary according to the season when electricity is used, where you live, and sometimes, by how much electricity you use. Let’s say that hydro in your area is 7¢ per kilowatt-hour

0.5 kWh x $0.07 = $0.035

So, using a lamp with a 100 watt bulb for 5 hours will cost you 3 _ cents. That doesn’t seem like very much at all! But normally, we use much more than just one lamp during the evening hours. Here is an example of electricity use in the typical household.